1. Field of the Invention
The present general inventive concept relates to an audio processing system, and more particularly, to a method and apparatus to detect voice activity by using a zero-crossing rate.
2. Description of the Related Art
In general, Voice Activity Detection (VAD) or End Point Detection (EPD) is used as a method of extracting voice activity from speech coding or speech recognition. In a conventional method of detecting voice activity, voice activity or a starting point and an end point of a voice signal are detected by using the energy of a frame and a zero-crossing rate of a frame. For example, the voice activity of a frame is determined when its zero-crossing rate is low, and non-voice activity of a frame is determined when its zero-crossing rate is high.
Here, since some types of noise or null signal lower the zero-crossing rates, zero-crossing rates for voice activity may not be distinctive from those for non-voice activity.
In other words, even though voice activity is detected using a zero-crossing rate in a conventional method, the detection may be false when some types of noise are added or there is no signal at all.